Presumably the OP is proposing something like a TPM attached to the image sensor that signs the sensor output or something like that. You can’t sign it because you can’t get the key out. The key could be per-camera and be a published list.
I suppose a dedicated fraudster could still stage an appropriate scene. An appropriately lit matte image might even suffice.
That's assuming they don't just have a backdoor inserted expressly for this purpose. Now only the rich or powerful can produce an "authentic" recording of an event and the same system can be used to hunt down whistleblowers and political enemies by looking up who bought the camera.
Keys could be stored in something like TPM on Camera, and could sign the image. The key could then be verified from the camera itself to prove the authenticity of the image.
If we as a society deemed it necessary, the camera manufacturer could also provide a list of keys for devices they have manufactured. And an image/key could be provided, and the manufacturer could verify the authenticity that way.
The TPM signing could be tied into the sensor hardware itself, making it difficult, but not impossible, to sign arbitrary images with the TPM.
The point of the key (as the for some reason dead comment points out), is not to prove who took the photo, but what device took the photo. Just as if someone stole a hardware token with a PGP key on could impersonate the owner. The key itself doesn't prove a person, just a device.
If a key was reset, a revocation of the original key could be issued, showing that the key was associated with the device for this particular time span. And then the new key registered.
This is ripe for abuse though, so resetting a TPM might not be accepted for this use case. I'm not certain in which case you'd want to reset a TPM for this use case though. Unless you took enough photos with the device to risk a birthday attack if you were using something like ECDSA.
Presumably the OP is proposing something like a TPM attached to the image sensor that signs the sensor output or something like that. You can’t sign it because you can’t get the key out. The key could be per-camera and be a published list.
I suppose a dedicated fraudster could still stage an appropriate scene. An appropriately lit matte image might even suffice.
Please note: A well-funded organization, like a government, can derive the keys from the TPM hardware using an electron microscope.
Also note that there are plenty of viable attack methods that don't even require key extraction, such as asking the TPM to sign arbitrary data.
That's assuming they don't just have a backdoor inserted expressly for this purpose. Now only the rich or powerful can produce an "authentic" recording of an event and the same system can be used to hunt down whistleblowers and political enemies by looking up who bought the camera.
Keys could be stored in something like TPM on Camera, and could sign the image. The key could then be verified from the camera itself to prove the authenticity of the image.
If we as a society deemed it necessary, the camera manufacturer could also provide a list of keys for devices they have manufactured. And an image/key could be provided, and the manufacturer could verify the authenticity that way.
The TPM signing could be tied into the sensor hardware itself, making it difficult, but not impossible, to sign arbitrary images with the TPM.
If I steal your camera while you're on vacation, do I then gain proof of ownership of your photos?
If I need to reset TPM, how do I reclaim photos I took previously?
The point of the key (as the for some reason dead comment points out), is not to prove who took the photo, but what device took the photo. Just as if someone stole a hardware token with a PGP key on could impersonate the owner. The key itself doesn't prove a person, just a device.
If a key was reset, a revocation of the original key could be issued, showing that the key was associated with the device for this particular time span. And then the new key registered.
This is ripe for abuse though, so resetting a TPM might not be accepted for this use case. I'm not certain in which case you'd want to reset a TPM for this use case though. Unless you took enough photos with the device to risk a birthday attack if you were using something like ECDSA.
[dead]
Finally a legitimate use for NFTs. /s
Or, you know, using the totally-real-picture camera to take a photo of an AI-generated scene?
Asymetric keys